Breech and firing mechanism for recoilless firearms



Oct. 4, 1949. w. J. KROEGER ETAL BREECH AND FIRING MECHANISM FORREGOILLESS FIREARMS I 2 Sheets-Sheet 1 FIG. 4.

Filed April 26, 1948 INVENTORS WILLIAM J. KROEGER. BY C. WALTON MUSSER.

TORNEYS fices in the gun's breech.

s e-we. 4 9 9;

PATENT OFFICE RECOILLESS FIREARMS William J. Kroege'r and ClarenceWalton Muscat,

Philadelphia, Pa.

Application April as. ms. Serial No. same i cum. (on. as 111) (Grantamended The invention described herein may be manufactured and used byor for the Government for governmental purposes without the payment ofany royalty thereon.

. The present application is a contination-in-' part of abandonedapplication Serial No. 536,590, filed on May 20, 1944, in the names ofWilliam -J. Kroeger and C. Walton Musser for Recoilless firearms,ammunition therefor, and ballistic design thereo Our invention coillesstype, and recoil guns wherein relates to firearms of the reit hasspecial reference to nonthe forces of rearward reaction that result fromprojectile discharge are neutralized by forwardly acting counterforcesslmultaneously set up by the propellent charges combustion.

Broadly stated, the object of our invention is to improve the design andextend the usefulness of recoilless guns tralization is effectedgenerated powder gas by a rearward escape of through openings or ori- Amore specific object chamber and breech constructions for suchrecoilless guns.

Another object isto provide improved designs for breech orifice nozzlesto facilitate orifice area adjustment and'the securing of zero recoil;at a desired performance level, and to neutralize gun twist with rifledbarrels.

wherein the named recoil neu-- is to provide improved .A further objectis to provide improved means for assuring substantially completecombustion of the powder .within the guns chamber, and for minimizingrearward discharge of unburned powder and fragments. w

A still further object is us provide improved means for firing the gunand for preventing the gun from being accidentally fired;

Other objects parent as the disclosure proceeds.

In the aforementioned parent application we disclosed a number offactors to be necessary for satisfactory operation of our inventiverecoilless firearm. In constructing one recoiiless firearm pursuant tothat disclosure we: gun's chamber of substantiallylarger diameter thanthe ammunition cartridge case which fits therein; (b) support thiscartridge case centrally and description hereof ed under the m of March3, 1888, as

ammo. ms; :10 o. a. 151) in this enlarged chamber solely from the twoends of the case; (c) provide in the gun's breech a rearwardly openingorifice of unique annular noz zle design and with ready adjustment foroptimum area; (d) use a cartridge case having a metal wall which isperforated throughout the length and circumference of the case and whichpermits discharge of propellent combustion gases radially against thechambers surrounding wall and thence rearwardly from the gun through theannular orifice of the-gun's breech; (e) pre-engrave the projectiles forready passage through the rifled bore of the gun's barrel; and (I) socoordinate the breech and firing mechanisms as to permit quick andconvenient loading andflring.

The invention to which the present specification is essentiallyrestricted is the specific breech closure structure used in thegun firstdisclosed by the aforementioned parent application. The presentinvention itself, together with illustrative embodiments thereof, willbest be understood from the following description taken in conjunctionwith the accompanying drawings wherein:

Fig. 1 is a view of the gun's rear end showing the breech block in itsclosed and locked position;

Fig.2 is a similar view except that the breech block is shown in theclosed, unlocked position;-

Flg. 3 is also a rear view, but shows the breech block in the unlockedand open position, having been swung away clear of the chamber;

Fig. 4 is-a view taken from line 4-4 of Fig. 1 to show details oftheorifice throat adjusting blocks plus other parts of the gun's breech andfiring mechanisms;

Fig. 5 is a view taken from line 5-5 of Fig. 1

to show the internal construction and other de-- a Fig. 5 to showfurther details of the breech block id) make the military and the tappethousing support therefor; and

Figs. 7-8-9 are enlarged showings of the hammer's split safety fixtureplus the slotted hammer and; hinge housing tubes therearound.

The complete recoilless gun Our inventive improvements are hereillustratively disclosed as being incorporated in a weapon of 5'! mm.caliber capable of a completely recoilless firing of projectiles. As thewill become apparent that our improvements may also be appliedto'iirearms of sizes, characters and shapes other than the ones heredisclosed and that the represented 57 mm. open-breech weapon thus hasbeen chosen only to illustrate and not to limit the inherently wideapplication and scope by which these improvements are characterized.

The illustrative recoilless firearm here shown consists of a barrel I5;an enlarged chamber l8 secured to the rear of this barrel; a breechblock I! partially closing the rear of the chambe a trigger handle l8for the user's right hand by which firing of the weapon is controlled; abarrelhandle l9 for the user's left hand by which training on the targetis aided; and a sight (not shown) for aiming the gun in aconventionalmanner.

As here represented. the guns trigger and barrel handles l8 and I 9 aresuitably clamped around the barrel I 5 at the angularly spaced locationshown by Figs. 1-2-3. Fig. 5 further shows trigger handle l8; barrelhandle i9 is not there shown. but it is situated between the triggerhandle and the muzzle (not shown) of the gun.

The chamber and breech As here shown, the guns chamber it takes the formof an enlarged cylinder which is afilxed at its forward end to the rearof barrel I5 in any integrally secure manner, as by the aid of screwthreads (not shown). If desired, this connection may be rendered morepermanent by a brazing of metal (not shown) around the entirecircumference 'of the juncture. Such brazing constitutes a gas-tightseal which prevents damage to the threads from powder leakagetherethrough; it also prevents relative turning between the barrel andchamber.

As the drawings also show, the guns breech block is a spider-likeelement removably secured within the rear end of chamber l6 andconstitutes only a partial closure therefor. The breech block isactually an apertured supporting member on which are fixed certain vanes52-58 whose form and function will later be described in detail. Ittakes the form of a cylindrical block I] which is radially spaced fromthe chamber walls in a manner to form a substantially annular orifice orventuri that leads from the chambers interior to the rear exterior ofthe gun. In Figs. 1 to 4 inclusive and 6 this annular orifice is shownat 22. As the drawings show, the annular orifice actually is interruptedby the four vanes 52-53; however, for all practical purposes the orificeacts as if it were a completely annular venturi as will later becomeevident, and therefore will herein be considered and referred to assuch.

Four locking lugs 29 extend radially from this central breech block I!and interfit with mating protrusions 30 on the chamber wall interior.These mating parts have the form best shown by Figs. 1 to 4 inclusiveand 6, and when engaged as in Figs; 1, 5 and 6 they securely lock thebreech block I! within the rear of the chamber.

The chamber wall spaces which circumferentially separate the lockingprotrusions 30 have a diameter larger than the maximum for the breechblock lugs 29, and this relation enables free longitudinal movement bythose lugs through the spaces named. This movement is utilized ininserting the breech block into the chamber and also in withdrawing ittherefrom, all in a manner to be described presently.

When inserted and locked within the chamber enlarged chamber I6 1. 5 and6 the breech block I! constitutes a firm support for the ammunition (seeFig. 5) which it helps to position within the chamber. The steel of theblock's central core structure is of suficient thickness and strength towithstand, with a factor of safety of. well over I, the maximum rearwardthrust exerted thereon duringfirine.

Cooperating with the guns barrel and the Just described chamber andbreech structure is ammunition having the unique perforated case shownin Figs. 4-5. As explained in greater detail in the aforementionedparent application, the purpose of the perforations 38 in the cartridgecase 33 is to permit the powder gases to issue therefrom in a radialmanner, so as to expand within the and become exhausted through theannular orifice 22 to the rear exterior of the gun with a torque equalbut opposite in direction to that caused by a projectile upon beingfired through the guns barrel.

In the loaded position represented by Figs. 4-5 the cartridge case headM is accordingly engaged by a mating recess 3i in the front of thebreech block. This recess 3i flares outwardly toward the front so asmore conveniently to receive the case head during loading. By itsengagement with the head, the rear of cartridge case 33 is centrallypositioned within chamber l6 and the entire case is restrained againstbackward move- 'ment. Thus positioned, the primer (not shown) carried bythe cartridge case head M is engageable by a firing pin 42 protrudingthrough the center of the breech block by firing mechanism later to bedescribed.

The annular orifice and adjustable nozzle Recoilless firearms of theopen-breech type here considered neutralize the forces of rearwardreaction by forwardly acting counterforces. In

as shown in Figs.

our improved weapon these counteriorces are produced by acceleration ofthe rearwardly escaping generated powder gases with an accompanyingpressure gradient within the chamber and venturi. Therefore, thepressure forces rearwardly acting against the obstructions presented bythe breech can be counteracted by the forwardly acting pressure forcesacting on the small annular forward portion of the chamber It, forwardlyacting drag forces of the projectile (not shown)'in the rifled (notshown) barrel l5 and by the forwardly acting force component produced bythe pressure of expanding gases in the conical and divergent portions ofthe earlier indicated annular orifice 22 between the guns breech blockI! and thefrear wall of chamber I6 wherein this block is secured.

As illustrated in Figs. 1 to 4 inclusive and 6, this annular orificeextends all the way around that block's central core or hub and isobstructed only by the four radial vanes 52-53 which commence centrallyfrom the common hub portion and terminate at their outward extremitiesin the breech locking lugs 29. All circumferential space separating lugs29 thus constitute the named annular orifice 22 which leads from theinterior of chamber l5 rearwardly to the exterior of the gun. I

Upon ignition of the propellent powder (not shown) and the resultantdischarge of the projectile (not shown) forwardly out of barrel l5,there is expelled through the perforations 38 of cartridge case 33combustion gases which are projected radially against thesurrounding'chaml1 and there actuated ber wall and .thence outof orificeof the represented nozzle" shape. Start- I ing with a relativelynarrow'radial width at its front or throat, the annular orifice flaresouther through the ,annularorifice now being; de-' wardly toward therearwith a total angle spread of approximately degrees; The exact value ofthis angle is chosen to yield the optimum of forward force component dueto an expansion of :the powder gases in passing rearwardly through theorifice as earlier explained. 'I'oo narrow an angle is found to cut downthe magnitude of this forward force component, while if the angle ismade too wide, the gases seem no longer to keep contact withthesteepness Of wall separation and much of the desired nozzle eflect againis lost.

For maximum effectiveness it would be desirable to extend the annularorifice, to a substantial axial dimension, but practical considerationsshow that acceptable performance is achieved when the nozzle orifice hasthe relatively short lengths which the drawings indicate (see Fig. 4

in particular). Thus, we prefer to select for the nozzle an axial lengthwhich gives a rearor discharge area of approximately four times the areaof the orifices front or throat area. Dimensions other than that shownmay of course be utilized with varying degrees of relativeefiectiveness.

In our achievement of complete neutralization of recoil we find thatthere exists an optimum ratio between the bore area of the gun and thethroat area of the breech orifice. This ratio is dependent primarilyupon the amount of expan- 4 sion obtained in the venturi 22 and to alesser extent upon such factors as the relative weights of the powderand projectile. In a firearm of the annular orifice type here disclosedthis ratio for As cut in the aforementioned application. we find itconvenient in practice to mark oneach block the particular value of boreto throat area ratio which its use (along with a companion block of thesame dimension) will give. Thus. one set of blocks will be marked 1.58;another 1.60; athird,1.62; and so on. Choice of the exact block size ismost effectively determined by trial firings in a pendulum or other gunsuspension which is free to swing and thereby indicate the presence,direction and magnitude of recoil, should same exist. In theillustrative 57 mm. weapon represented. zero recoil has been found torequire the use of a pair of blocks which I give a bore-area tothroat-area ratio of the order of 1.60. With such adjustment the nozzlethroathas a total area which is approximately one-tenth of thecartridgeperforation area.

Neutralization of rotational .reaction' Firearms with rifled barrelsexperience a rotational reaction by virtue of the spinning motion thatfiring imparts to the projectile. In the particular gun shown the gunbarrel i5 happens to have been rifled (not shown) with a right-handtwist, the result being to give clockwise rotation toprojectiles firedtherethrough, and this righthand acceleration of the projectilesmass'will impart counterclockwise torque of equal magnitude to thebarrel. Our improved weapon includes provision for neutralizing suchreactive torque by causing the explosive gases which rearwardlydischarge through the annular breech orifice 22 to impart to the weaponcounterbalancing torque of the same magnitude as that which zero recoilwill lie within the range of about 1.35

to about 1.70.

recoil. In the illustrative arrangement disclosed,

this provision takes the form of a pair of orifice blocks 63 aifixed toflattened portions on oppos-l ing sides .of the inner nozzle wall andthere firmly held by any suitable means such as the represented bolts 64(see Fig. 4). with countersunk 55 heads. While occupying such aportionof the total orifice area as is needed to supply the necessaryadjustment, these blocks 63 do not alter the basic nozzle shape thereof,and hence they constitute a particularly efficient means of effectingthe required adjustment.

Themaximum throat area is of course realized when both blocks 63 areremoved; hence the annular orifice is designed to afford a throat arealarge enough to meet the maximum requirements under that condition.Applying the figures earlier stated, this might give a bore-area tothroatarea ratio of the 1.35 lower limit. To change 5 this ratio to itsotherextreme of the named 1.70 maximum, it is merely necessary toinstall at 63 orifice blocks of size sufficient to cut down the totalthroat area by the requisite amount; and to obtain ratios ofintermediate values there may be substituted adjusting block 68 ofvarying intermediate size.

the rified barrel imparts to the projectile (not shown). This provisionis effected by so specially shaping the rear tail pieces of the breechblock vanes 5253 that the gases passing through orifice 22 have angularmomentum imparted thereto. (Of course, if the gun barrel happened tohave been given a left-hand twist for its rifiing, the same result couldbe achieved by directing or shaping the vanes 52-53 in a directionopposite to that shown, thereby imparting to the rearwardly escapinggases. a clockwise torque which will counterbalance the counterclockwiserotation given by the gun to projectiles fired therethrough.)

As the drawings show, each'of these breech block 'vane tailpieces tapersin the general manner shown from a maximum cross section beneath lockinglugs 29 rearwardly toward a minimum and much narrower width at the rearex-p treme thereof. If this taper were the same on both sides of eachtailpiece, the discharge of powder gases therepast would exert norotative force ,in either direction, but instead the side forcecomponents set up by the expanding gases would be the same in bothdirections and hence completely counteract one another.

To obtain the desired torque neutralization we modify the tailpieceflaring to the extent indicated by the drawings. From those drawings itcan be seen that the angle on the one side of each tailpiece differsfrom the angle on they other side in the proper amount and direction togive the gases a counteracting spin about the gun axis.- The effect isto impart to the axes of breech orifice opening 22 small angulardisplacements (all in the samerotative sense) with respect to the mainaxis of the guns barrel l5 and chamber [6.

In consequence, the sides of these vanes having the smallest angle haveimparted thereto a stronger side or tangentialthrust from" the expandinggases than-do the opposite vane sides, andthere thus is imparted to thebreech block a torque-counteracting that applied by the pro- Jectile.Only the relatively small degre of angular unbalance indicated is foundsufilcient to make the thus imparted torque of the same magterclockwiserotation moves the locking lugs out nitude as the barrel l imparts tothe projectile (not shown) in advancing it through the rified bore.

During firing the breech block I! transmits this neutralizing torque tothe chamber and thence to the barrel, and in this-way all forces ofrotational reaction are neutralized in a very simple, yet highlyeffective manner. In the illustrated weapon the-combustion gases thatfiow rearwardly through the breech orifice openings 22 have impartedthereto a counterclockwise spin which is opposite to the clockwise spingiven by the gun's right hand rifling (not shown) to the forwardly firedprojectile (not shown). As the vane structure of the nozzle-formingportion of the breech block is asymmetric in relation to the gun's axisfor each Venturi opening, a different amount of expansion tends to occurfor opposite sidesof each venturi for axial gas flow. Therefore, thecenter line of the gas flow through each nozzle is tangentialiydiverted'in a circular pattern about the axis of the gun. Theaccompanying gas reaction" torque exerted on the gun-is clockwise andthus neutralizes the counterclockwise projectile reaction" torquereceived by the barrel IS.

The breech block carrier and lock mechanism Explanation has already beengiven of how the breech block I1 is secured in the rear of chamber I 6by the aid of that block's locking lugs 29 and the mating protrusions 30on the chamber interior. In the locked position represented by Figs. 1,5 and 6, this support is all that is needed to hold the breech block inplace, and it is fully adequate to restrain the maximum chamberpressures which combustion of the propellent charge (notshown) sets up.

To facilitate loading, and removal of the cartridge case 33 afterfiring, provision is made for unlocking this breech block l1, rearwardlywithdrawing it from the chamber l6 and swinging it out of alignment withthe chamber interior to some downward position such as that shown inFig. 3. Aiding these actions is an operating member which illustrativelytakes the form of a pair of handles 49 which protrude from the breechblock, a radial support member shown in the form of a tappet housing '50which extends into that blocks center, and a lateral support membershown in the form ofa hinge housing 5| (see Fig. 5) which interconnectsthe radial member 50 with the outside of the gun's chamber l6. Theseelements constitute mechanism by which the breech block continues toreceive support from the gun after it has been withdrawn from thechamber.

The named operating member represented in the drawings by handle 49protrudes in the manner shown from radial vanes 52 which extendrearwardly from the breech block I1 by a distance somewhat greater thando the remaining two breech block vanes 53. By these handles 49 anoperator may rotate the breech block through the small angular distanceindicated at d in Fig. 6. In the gun here shown this range of angularmovement is of the order of '35 degrees.

Clockwise rotation serves to engage the breech block locking lugs 29behind the mating protrusions 30 of the chamber and thereby secure thebreech block therein as earlierexpl'ainedf counof engagement with thechamber protrusions and into the circumferential regions betweenprotrusions. In the latter position the breech block I! is free forrearward withdrawal from the chamber.

Serving to support the breech block upon such withdrawal is the radiallydisposed tappet housing earlier mentioned. This housing is attached atits outer end to a pivot tube or hammer 110118? ing sleeve 56 slidingand turning in the stationary hinge housing or support tube 5| earliermentioned as being fixed to the outside of chamber I 6; from thisattachment the radial tappet housing extends through a cutaway portionin a rear rim 51 of the breech block to that block's center where thesun's firing pin 42 (see Fig. 5) is mounted.

There, circular openings in the front and rear of this radial member 50accommodate opposing bosses 58 and 59 (see Fig. 5) projecting from thebreech block and from a cover plate 50 therefor. This cover plateis'secured to the block by the aid of three bolts 6i which pass throughthe plate and into tapped openings in the block metal thereby holdingthe plate firmly in a mating recess in the block's rear rim 51. v

The rotatable connection thus established permits the earlier namedangular movement of the breech block II with respect to the chamber l6,and also with respect to the tappet housing 50 which extends into theblock's center from the chambers outside. In this way application ofclockwise turning force of handles 49 effects locking of breech lugs 29behind the mating protrusions 30 of chamber l6; and application ofcounterclockwise turning force disengages those lugs from the chamberprotrusions and thus frees the breech block for rearward withdrawal fromthe chamber. Both of these turning movements are limited in their extentby the sides of the represented opening I05 in the wall of the rearbreech rim 57.

As aforesaid, the illustrated weapon is represented as having right-handrifling (not shown). In such a weapon, the gas forces applied (asearlier explained) to neutralize torque reaction exert thereby maintainthe locked position thereof during firing. Where the gun can be rifledwith lefthand twist, then the locked position of the breech block shouldof course be at its counterclockwise limit of turning movement.

The earlier named hinge housing sleeve 5| is secured to the outer wallof chamber i6 by brazing or other permanent form of attachment. Thishinge housing is continued forwardly to the trigger handle I8 and withinit the smaller diameter hammer housing sleeve 56 is carried (see Figs. 5and 8) in a manner permitting both radial and lengthwise movement. Thisform of carriage permits the affixed tappet housing 50 to bewithdrawnrearwardly with respect to the hinge housing 5| and also to be rotatedwith respect thereto.

Once, therefore, breech block I! has been disengaged from the chamberportrusions 3!], application of rearward force to handles 49 causes thebreech block l1, tappet housing 50 and hammer housing 56 allsimultaneously to be moved back away from the rear of chamber It.

The range of this backward movement is sufiicient to allow completeclearance of the breech block with respect to the chamber, and when thishousing'may both be swung downwardly'to the position shown in Fig. 3. Insuch position the entire interior area of the chamber I6 is un-'obstructed in a way permitting ready insertion of the projectile (notshown) and cartridge case 33 into the gun, or ready withdrawal of aflreda cartridge case from the gun's chamber.

To re-insert the breech block into the chamber it is merely necessary toswing the tappet housing 50 clockwise and upwardly about its in whichthe locking lugs 29 thereof engage with the chambers mating protrusions(as best shown inFigs.1and 6). y

Close fitting of the radial tappet housing 50 against the end of thehinge housing 5| when the breech block I1 is locked within thegunschamber may be secured-in any desired manner such as by the aid ofshims of the type shown at 66 in Fig. 1

:The firing mechanism For igniting the ammunition propellent charge (notshown) atthe will of an operator, use may closed). Here represented byway of illustration is a unique mechanical type of firing mechanism bythe aid of which an operator may fire the weapon by a simple squeezingof the trigger handle Hi. In the disclosed arrangement, the

firing pin fl-carried by the gun's breech block l1 (see Fig. 5) receivesthrough a tappet 51, a firing blow created by the rearward movement of-arod-shaped hammer 6 8. The force incident to this rearwardmovementoriginates in a compression spring 59 and is made available for firingthe gun when a trigger 10 protruding from the front of trigger handle I8is compressed into that. handle. 7 a

The just named tappet 51 (see Figs. 4-5-6) is mounted on a rocker pin 1|within the radially disposed tappet housing 50; As earlier describedthis radial member 50 also constitutes the support for the breech block|1 when withdrawn from the weapons chamber l6; serving to close thehousings back isa removable'cover-13 held in place by an overlapping ofthe breech block cover plate '50. A tappet retractor spring 14 urges theouter end of. this tappet tothejorward travel limit shown in Fig. 5, andin that condition the inner. end of the tappet is separated from therear of firing pin 42 by-the substantial" clearance which Fig. 5 alsoshows.-

'The illustrated hammer 68 takes the form of a long, slender rod ofsteel or other suitable metal slidably contained (see Fig. 5) within thehousing sleeve 56 earlier described as constitutinga support for theouter. end of the radial tappet housing 50. As earlierexplained, thishousingsleeve or pivot tube 56 is-rotatably and slidably concondition isrealized the breech block and tappet companion hammer housing 56likewise e :tends 'within the stationary hinge housingil from the rearlocation-of tappet housing 50 to the forward location of trigger handleit. At the said forward location the housing or pivot tube 58 terminatesin a spring retainer 15, taking the form of the represented sleeveattached to the tube end by a thread connection. At the rear end thehammer is slidably supported by a ham- 10 mer bushing I05.

5 within the space thus made available. The for- The inside diameter ofthe hammer housing 551s somewhat larger than the outside diameter of thehammer rod which it surrounds, and

the earlier named hammer spring 69 is carried ward end of this hammerspring abuts against the retainer 16, while the rear end of the springexerts force against a spacer sleeve 11, also slidably carried betweenthe central hammer 68 and the housing sleeve 56 which surrounds it.

of length greater Adjacent to this spacer 11 on the side opposite to thespring 'is a reduced diameter section of the hammer 5'8, and surroundingit is a split safety fixture made up of two parts 19- 80 5 (seeFigs. 5and 7) having the mating character shown in the drawings.

These two parts are housed within the hammer tube 56 for restrictedslidable and rotative movement, and they also permit the hammer 88 tomove axially there 3 through along the hammers reduced diameter be madeof any suitable firing mechanismoeither s electrical (not shown) ormechanical (here dis I portion. v

Radially protruding frompart 19 is a safety arm 8| which extends throughregistering slots 52 and 55 in the concentrlcallydisposed hammer andhinge housings 56 and 5|, respectively, to the outside for manipulationby the operator. The named slots 62 and 55 have .the characterillustratively shown in enlarged form by Figs. 8 and 9, andduringcooking and firing of the 40 hammer rod 58 theseslots cooperate with thesafety arm 8| in a manner to-be explained presently.

The slot 55 in the outer'or hinge housing 5| has the substantial widthlater named and is than the axial distance through which hammer 68 andsafety arm 8| ,move during cocking and firing. The cooperating slot 62in hammer housing'56 is comprised of two parts identified as 52A and 623(see Figs. 8-9)- This slot 62 is wide at its front (62A) and narrow 5!!enable the safety fixtures at its rear (52B) and has 'on the narrow sidethereof a total length somewhat greater than that of housing 5ls slotthe wide region of this hammer housing slot is sufficiently long to19-80 to be inserted therethrough for assembly around the reduceddiameter portion of hammer 58. This hinge housing slot 55' and thehammer housing slot 52 at its widest section (see Fig. 8) both have 50 atotal circumferential width of somewhat more than 90 degrees. Incooperation with safety arm 8| these two slots serve to restrain thedownward swinging movement of the tappet housing 5ll'(see Fig. 3). to anangle ofionlyslightly more 65 than that 90-degree limit.

tained within .the outer hinge housing tube 5| It" will be seen from thedrawings that the Under the after loading conditions represented in Fig.5 the hammer 58 is cocked to the forward position where a latch head 83thereof is advanced past trigger 10s sear 84; the hammer (0 spring 59 iscompressed between hammer housing 55's forward retainer 16 and therearward spacer 11; that spacer abuts parts 19-80 and through them isheld against rearward movement by engagement of sa'f'ety'arm 8| with thehammer housing 55s short lower recess 12 (see Fig. 8);

hammer.

- 12 of the short slot 62A in tube 56 (see Fig. 8)

and rotated upwardly into alignment with hammer housing 56's long slot623. This permits the 'spring 69 and spacer H to push the safety fixture'|980 backwards to the point where the rear thereof abuts the largerdiameter of the hammer 68. That hammer now receives the rearward forceof the spring and pulls latch head 83 against the trigger sear 84 (seeFig.

Under these conditions a compression of the trigger into the housing l8therefor will release the hammer allowing the compressed spring rapidlyto move it backwardly along with spacer I1 and the safety fixture. Bythis movement the safety arm 8| moves in the narrow slot 823 of housingtube 56 to the rear limit thereof. This limit is reached just before theend of hammer 68 has contacted tappet 61, and at that point thespringscompressive force is removed from the The momentum of acquiredmotion causes the hammer to continue to move back through safety fixture79-80 and by striking the outer end of tappet 81 to impart a blow to thefiring pin 42 and thereby detonate the primer (not shown) inthecartridge case.

. nism is returned to the original or "after load- To re-cock the hammerin preparation for the firing of another round, the breech block I? isby counterclockwise rotation disengaged from the chamber 56 andrearwardly withdrawn by handles 49. Tappet housing 59 transmits thisrearward movement to the hammer housing 56 and pulls retainer '56backwards in the stationary hinge housing 5|. Safety arm 8i, nowabutting (see Fig. 9) the rear of hinge housing 5ls slot 55, restrainsthe spacer if from rearward movement, and in consequence, the hammerspring 69 now becomes compressed.

By this rearward movement the narrow slot- 62B in hammer housing 56 isdrawn past the safety arm 8| into a position of housing 58 where thatsafety arm is in the area of housing 56s wide forward slot 52A. Incidentthereto is a complete clearance of the breech block 81 from the end ofchamber i 6, and a resultant freedom of swinging movement of this blockdownwardly to the position shown in Fig. 3.-

Such a swinging of tappet housing 56 rotates the hammerhousing 56counterclockwise in the stationa y hinge housing 5|. During thisrotation of the hammer housing 56, the safety arm 8| continues to abutthe rear of hinge housing 5 as shown dotted by Fig. 9, and thus therecess 12 in the short slot 62A of housing 56 (see Fig. 8) is b oughtinto alignment with that arm. Release of breech block withdrawing forcenow allows the hammer spring 69 to pull the hammer housing 56 forwardand thus re-engage this housings short slot 62A recess 12 with arm 8|,as shown by Fig. 8. Subsequent swinging of the br ech block and thetappet housing 50 inwardly (clockwise) into alignment with the weaponschamb r rotates housing tube 56 and safety arm 9| clockwise in thestationary hinge housing 5|. He the breech se ted into the end ofchamber l6 by movement w ic carr es hammer, housing 55. safety arm BIblock may be forwardly rein sive blow to thefiring pin ing" condition ofFig. 5 with which this description started.

Firing pin, leader's and trigger safeties The gun operator's or"loader's safety has already been described in part. It utilizes thesafety arm 8|, which at the. end of each cocking occupies the afterloading position shown in Fig. 5. With the safety arm 8| in thisposition pulling of the trigger I9 is ineffective for releasing thehammer, and no firing of the weapon is possible.

Before the weapon can be fired it is necessary for the loader of the gunto push safety arm 8| forward out of housing tube 56's slot recess (seeFigs.'8-9) and rotate it counterclockwise into alignment with thattube's long narrow slot 623, thus effecting the "armed position (notshown). When that has been done the compressive force of hammer spring69 is transferred to the trigersear "84, and withdrawal thereof from thelatch head 83 allows the hammer to fly backwardly'and cause tappet t'ltoimpart a percus- 2.

In addition to this loaders safety, our improved weapon here disclosedalso includes: (a)- a trigger safety; and (b) a firing pin safety.

The trigger safety utilizes mechanism asso-. ciated with the trigger 10within the trigger handle l8. This trigger is mounted for rotation abouta support point 86 (see Fig. 5), and the lower portion of the trigger isheld forwardly by, a leaf spring 81. This spring urges sear 84 upwardlyinto engagement with the hammers latch head 83.

The trigger handle l8 comprises two sections fastened to a carriermember 94 which is fixedly mounted on barrel l1. Also carried by thetrigger handle I8 is a trigger guard 89, which completely surrounds theexposed portion of trigger i0 and requires that pulling movement beimparted to the trigger through application to this guard. A fasteningferrule 90 for this guard is borne by the carrier member 94 slightlybelow the corresponding support 86 for the trigger.

The trigger safety fixture is fully described in the aforementionedparent application and therefore needs no complete description here. It

. by a trigger safety spring (not shown). Key 92 fits into a mating slot(not shown) in one side of the trigger guard 89 and is prevented fromrotational motion by fitting into the slots in the stationary centralplate 94 of the trigger handle. As long as the safety button 9|protrudes from the side of handle I 8. the just mentioned spring (notshown) holds half of this non-rotating locking key 92 in the slots (notshown) in the guard condition the guard is locked side 89. Under thisagainst rearward movement into contact, with trigger 10, and applicationof pressure to the guard 89 is prevented from effecting triggeroperation.

When, however, the safety button 9| .is depressed the locking key 92 ismoved completely within the handle plate 94 and out of engage-' mentwith the trigger guard 89. Under this condition the guard is freed forbackward movement and'application of pressure thereto then becomeseffective for pulling the trigger and firing the weapon. In view of thefact that the safety spring (not shown) is continuously acting asaforesaid to move the safety button 9| into the safe position, thebutton must be kept depressed by the gunner during the entire'time it isdesired .to keep the trigger guard 83 free for actuation of the trigger.Y

The third or firing pin" form of safety involves the hammer tappet 61and engagement of the 'inner end thereof with the 'firing pin 42 carriedby the weapons breech block II. Surrounding the end of this firing pinis the rearward boss 58 (see Fig. 5), earlier described as fitting intoamating opening in the inner end of the tappet housing 50.

In order that the tappet 31 may strike the firing pin, this circularboss 58 is provided with the slots 65 represented in Figs. 4-5. Whenproperly aligned with the tappet this slot permits such forward movementthereof as is necessary to impart a detonating blow to the firing pin.

. This proper alignment (as shown in Fig. 4) exists only when the breechblock I I is locked within chamber It by clockwise rotation of lugs 29behind the chambers mating protrusions 30.

, When the breech block's lugs are disengaged from.

the chamber, this breech boss 58 is rotated to a position where thedescribed slot therein no longer aligns with the tappet, and under thiscondition the boss wall mechanically blocks advancement of the tappetinto contact with the firing pin.

Hence, even though thebreech block I I may be inserted into the chamberit is possible to fire the weapon .only after there has been imparted tothat block sufficient clockwise rotation to effect secure locking in thefiring position.

Loading and firing From the foregoing it will be seen that we havprovided an improved recoilless firearm which ofiers special advantagesin connection with both jdetonation of the primer and ignition of thecharges contained within the cartridge case..

The resultant combustion of the propellent charge (not shown) dischargesthe projectile (not shown) and at the same time ruptures a frangiblelining 33 (see Figs. 4-5) which lines the interior breech venturi andthence to the rear of the weapon. In a manner already explained inpart,this escape of explosive gas-sets up counteriorces which neutralizerecoil and thus permit the weapon to be fired either from the shoulderor from a light tripod or other'mounting.

The perforated wall metal of the cartridge case 33 remains intact duringthis firing and is not ruptured or otherwise damaged. Indications arethat, the pressure within the chamber IS on the inside and outside ofthe cartridge case wall.

equalizesjitself early during the burning cycle.

, chamber.

loading and firing. To place the ammunition round within the weapon itis merely necessary to unlock the breech block I! by turning itcounterclockwise from the Fig. 1 to the Fig. 2 position, withdraw itfrom chamber l6 and swing it downwardly to the position shown in Fig. 3,thus completely freeing the chamber opening.

The ammunition round is now inserted into the opened chamber and therear of the barrels bore. When the projectile (not shown) is positionedin the barrel bore (not shown) centering support is imparted to theentire cartridge case 33 and allows the rear head 4| thereof to drooponly slightly from the rear chamber center. The breech block I! is nowmoved forwardly into the chamber. In approaching and engaging with thecartridge case head II, the flared recess 3| in the breech block's frontserves to center the head thereby constituting a second support for thecartridge case. Clockwise rotation of the-breech block by handles l9'nowlocks it into the chamber with the front shoulder (not shown) of thecase in abutment with the barrel, and the case head ll in abutmentwith-the breech block, the primer (not shown) in alignment with thefiring pin 42 and the entire cartridge case 33 centrallypositionedwithin the surrounding chamber I6.

Thus, after the case has been fired, some of the openings 38 may befound to have thin films of ash either partialiyor completely coveringtheir area.

Subsequent withdrawal of the fired cartridge case from the chamber iseffected by unlocking the breech block, withdrawing it rearwardly, andswinging it downwardly out or register with the This frees the firedcase for ready withdrawal from the chamber and conditions the weapon forinsertion andsubsequent firing of another ammunition round.

Summary I From the foregoing it will thus be seen that we have sodesigned and extended the usefulness of non-recoil guns wherein theforces of rearward reaction that result from projectile discharge areneutralized by forwardly acting counterforces simultaneously set up byrelease of powder gases through an orifice in the guns breech; that welevel; that we have assured substantially complete combustion ofthepowder within the guns 'chamber and have minimizedthe rearwarddischarge of unburned powder and fragments; and

The weapon is now ready for firing, and'upon that we have providedimproved means for firing the gun andfor preventing the gun fromaccidentally being fired.

Our inventive improvements thus are capable of wide application andhence are not to be restricted to .the specific form here shown anddescribed by way of illustration. a

We claim:

1. In a firearm, the combination of a barrel, a

chamber communicating therewith, a breech block movable into and out ofthe rearward portion of said chamber and rotatable for lockingengagement therewith, coacting interlocking members formed on peripheralportions of said breech block and the inner wall of said chamberengaging said support for movement lengthwise of said chamber andbarrel, and means extending radially from said breech block to saidcompanion member and constituting a connection which permits rotativemovement of the breech that block when same is withdrawn from thechamber. g

2. In a firearm, the combination of a barrel, a

assa'aai means effective to engage said hammer and latch it in' its saidcocked position against the force I block within the chamber and whichsupports chamber communicating therewith, a breech block movable intoand out of the rearward portion of said chamber and rotatable forlocking engagement therewith, coacting interlocking members formed onperipheral portions of said of said spring.

5. In a firearm, the combination of a barrel, a

chamber communicating therewith, a breech block movable into and out ofsaid chamber, a firing pin in said breech block, a support tube securedto the outside of said chamber and extending lengthwise thereof, a pivottube within said support tube carried thereby and free to Slide and turnwith respect thereto, a radial member connecting said breech block andpivot tube whereby movement imparted to said block is transmitted tosaid pivot tube, a tappet arm carbreech block and the inner wall of saidchamber and being engageable and disengageable upon locking andunlocking rotations of the breech block within the.chamber, a supportfor said breech block secured to the outside of said chamber, acompanion member rotatively and slidably engaging said support formovement lengthwise of said chamber and barrel, a radial memberextending from said breech block to said companion member andconstituting a connection which supports the breech block when same iswithdrawn from the chamber and which also permits the block to berotated when within the chamber, a firing pin disposed in said breechblock, a tappet arm carried by said radial memher and spannin thespacebetween the axis of the firing pin and the axis of the supportssaid companion member, and a hammer element movable axially of saidcompanion member to strike said tappet arm and operate said firing pin.

3. In a firearm, the combination of a barrel, a

chambercommunicating therewith, a breech block movable into and out ofsaid chamber, a supporttube for said breech block secured to the=0utside of said chamber and extending lengthwise thereof, a pivot tubewithin said suppfirt tube carried thereby and free to slide and turnwith respect thereto, means operatively connecting said pivot tube tosaid breech block whereby movement imparted to the block is transmittedto said pivot tube, a firing pin in said breech block, a tappet armcarried by said connecting means and extending betweenthe axis of saidfiring pin and the axis of said pivot tube, and a I hammer disposedwithin the pivot tube and movable axially thereof to engage said tappetarm transmitted to said pivot tube, a firing pin in said breech block, atappet arm carried by said connecting means and extending between theaxis of said firing pin and the axis of said pivot tube, a hammerdisposed within said pivot tube and movable axially thereof between aforward cocked position and a rearward released position .where thehammer engages said tappetand thereby operates the firing pin, a springalso within said pivot tube for urging said hammer from said cocked tosaid released position, and trigger ried by-said radial member andextending between the axis of said firing pin and that of said pivottube, a hammer within said pivot tube movable lengthwise between aforward cocked position and a rearward released position where thehammer engages said tappet and thereby operates the firing pin, a safetyfixture carried by said hammer and protruding through registering slotsin said pivot and support tubes, a hammer spring within said pivot tubecompressible between a forward extension of the pivot tube and saidsafety fixture, means including said fixture and the said tube slotsthrough which the fixture protrudes for causing rearward movement ofsaid breech block and pivot tube to compress said hammer spring, and atrigger eifective upon forward return movement of said breech block andpivot tube to engage said hammer and latch it in its said cockedposition against the compression of said spring.-

6. In a firearm, the combination of a barrel, a chamber communicating.therewith, a breech block movable-into and out of said chamber, a firingpin in said-breech block, a support tube secured to the outside of saidchamber and extending lengthwise thereof, a pivot tube within saidsupport tube carried thereby and freeto slide and turn with respectthereto, a radial .member connecting said breech block with said engagessaid tappet and thereby operates the firing pin, a fixture carried bysaid hammer and including a safety arm which protrudes throughregistering slots in said pivot and support tubes, a hammer springwithin said pivot tube compressible between a, forward extension of thepivot tube and said hammer fixture, means ineluding said fixtures safetyarm and the said tube slots through which that arm protrudes for causingrearward and swinging movement of said tube-supported breech block tocompress said hammer spring and for causing forwardreturn movement ofthe block to engage said arm in a safety notch in one side of said pivottube slot, and a trigger efiective upon manual movement of said safetyarm out of said notch to engage said hammer and latch it in its saidcocked position against the compression of said spring.

7. In a firearm, the combination of a barrel, a chamber communicatingtherewith, a breech block movable into and out of said chamber andengageable therewith and disengageable therefrom upon locking andunlocking rotations with firing pin, a hammer movable to strike thetappet 10 and operate said pin. resilient means normally urging thetappet am away from the firing pin, and means mechanically positionedbeside said protruding pin to permit contact thereof by said tappet whenand only when said breech block occupies its locked rotative positionwithin the chamber.

WILLIAM J. KROEGER.

CLARENCE WALTON MUSSER.

No references cited.

